An Amplify-and-Forward Full-duplex Cooperative Relay Scheme for Low-latency Downlink Transmission in CRAN

This letter proposes a novel full-duplex-enabled cooperative relay scheme to reduce the downlink delivery latency in cloud radio access networks (CRAN). Specifically, remote radio heads (RRHs) are deployed with full-duplex capability and work in Amplify-and-Forward mode so that they could receive signals from the baseband signal processing unit (BBU) and forward to the user groups immediately, which can efficiently decrease the waiting and processing delay. Beyond the proposed scheme, we move forward to jointly optimize the transmit/receive beamforming vectors of both BBU and the RRHs with the target of minimizing the maximal delivery latency among all user groups. The formulated problem is a multivariable coupling problem and difficult to solve. To deal with it, we propose an efficient successive convex approximation iterative algorithm. Simulation results show that our proposed scheme could reduce the delivery latency compared with other schemes.